JPS62228635A - Internal combustion engine employing alcohol as fuel - Google Patents

Abstract

PURPOSE:To improve the thermal efficiency over the entire load area by performing the switching control between a direct injection apparatus for injecting alcohol fuel into a combustion chamber and an apparatus for feeding a reforming gas to an intake pipe according to the operating conditions. CONSTITUTION:An injection nozzle 4 is provided to a combustion chamber so as to feed alcohol in a tank 2 through an injection pump 3. The alcohol in the tank 2 is also fed as a reforming fuel from the downstream of an intake control valve 11 through an alcohol pump 5, an evaporator 6, a reformer 7 and a solenoid flow control valve 8, A controller 12 detects the operating conditions of an engine and fully opens the intake control valve 11 under a heavy load area so as to feed alcohol only through the injection valve 4 while the intake air quantity is controlled by the intake control valve 11 under an intermediate load area and a small quantity of alcohol is fed through the injection valve 4 so as to feed the majority of fuel as a reforming gas under a light load area. Consequently, the thermal efficiency is improved over the entire area.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an internal combustion engine that uses alcohol as fuel.

<Prior Art> Internal combustion engines in which petroleum fuel in an internal combustion engine is replaced by alcohol are known. Known internal combustion engines that use this alcohol as fuel use a reformer to convert the alcohol into CO and H21.
This gas is decomposed and converted into flammable reformed gas with a high calorific value, which is then supplied to the engine.There is no diesel type.

<Problems to be solved by the invention> Internal combustion engines that use reformed alcohol gas as fuel have difficulty in starting, and if a direct injection forced ignition method using liquid alcohol spray is used, the engine will outperform a diesel engine in a high load range. thermal efficiency can be obtained, but it decreases in the low load range. Therefore, it is not possible to obtain thermal efficiency as high as that of a diesel engine in the entire load range from low to high loads, and the stability of combustion and ignition at low loads is poor, resulting in poor performance and exhaust emissions. .

Further, when alcohol reformed gas is supplied from the intake pipe of the above-mentioned forced ignition type engine, there is a problem that abnormal combustion such as premature ignition occurs under high load, making the engine inoperable.

Means for Solving the Problems> The present invention provides an internal combustion engine that solves the above-mentioned problems, and the gist of the structure is to inject alcohol fuel into the combustion chamber in accordance with the operating conditions of the engine. It has a two-system fuel supply device that can be switched, a direct injection means for spraying liquid into the combustion chamber, and a means for passing reformed gas and supplying it to the intake pipe. It is equipped with an intake control valve and its control device that control the intake amount, and a spark plug that ignites the fuel.

Function> The present invention injects HC directly at high and medium loads of the engine, directly injects a small amount of fuel at low loads, and supplies mostly reformed gas, and in medium and low load areas. The fuel supply system and the intake air control system are adapted to the operating conditions of the engine so that the air flow rate is maximized by controlling the amount of intake air and the thermal efficiency of the engine is maximized.

<Example> Hereinafter, an example of the present invention will be described based on the drawings. In FIG. 1, 1 is the engine body, 9 is an intake pipe, and 18 is an exhaust pipe. This engine body 1 has an injection nozzle 4 and a spark plug l.
It is equipped with O. Further, in the intake pipe 9, an intake control valve 11 is provided which is controlled to open and close by a controller 121, which will be described later.

2 is a liquid alcohol tank. The alcohol fuel in the tank 2 is supplied to the engine body 1 through two fuel supply systems 1. One system is
This configuration has a tank 2 and an injection nozzle 4 connected via an injection pump 3. Another system is to supply alcohol vapor to the evaporator 6 using an alcohol pump 5t, convert the alcohol vapor into flammable reformed gas via a reformer 71 that uses exhaust heat, and then convert the alcohol vapor into flammable reformed gas. This is a configuration in which the air is supplied from the intake control valve 11 into the intake pipe 9 on the engine body 1 side. An electromagnetic flow control valve 8 is provided in a flow path for supplying reformed gas from the reformer 7 to the intake pipe 9.

12 is a controller. This controller 12 detects engine operating conditions (engine rotational speed N1, engine negative load, etc.) and controls the injection pump 3, alcohol pump 5, electromagnetic flow control valve 8, and igniter 13. The igniter 13 controls the ignition timing of the spark plug 10. 14 is an exhaust catalyst, 15 is a muffler, 16 is cooling water for the evaporator 6, and 17 is an accelerator pedal.

Since the present invention has the above-described configuration, the two fuel supply systems and the intake control valve 11 are arranged in accordance with the operating conditions of the engine.
The following operations are performed, and the operations are optimally controlled by the controller 121. That is, depending on the opening degree of the accelerator pedal 17, the controller 12 determines the engine load as shown in FIG.

In the high load region 1 (Th - Tm), fuel is supplied only by the alcohol injection system, and the intake control valve 11 is controlled to remain fully open. Medium load range 11 (Tm-T
In l), fuel is supplied only by the alcohol injection system, and the intake air amount is controlled by the intake control valve 1N to improve thermal efficiency and
The excess air ratio is set to 1 so that exhaust gases such as NOx are layered.
．． Control within the range of 0 to 2.5.

In the low load range [(Tl − To ), a small amount (0 to 20%) of fuel is supplied by the alcohol injection system, and most of the fuel is supplied by the reformed gas supply system. In addition, the intake air amount is controlled by the intake control valve 11 until the excess air ratio is 1°θ~
It is controlled to be within the range of 2.5. Incidentally, when the cooling water temperature is low at the time of starting and alcohol vapor cannot be generated in the evaporator 61, fuel is supplied only by the alcohol injection system in the low load region (2) in the same manner as in the medium load region (2).

The action of the controller 12 is based on input signals such as the Kumagaki rotation signal N,
Accelerator opening signal ■, exhaust temperature T1, chilled water temperature T2,
The reforming catalyst temperature T3 is detected, and the injection timing and injection amount of the injection pump 3, ON-OFF of the alcohol pump 5, ignition timing of the igniter 13, valve opening of the electromagnetic flow control valve 8, and valve of the intake control valve 11 are determined. Optimally control each opening. In addition, the controller 12 inputs an input signal and stores it in advance in a ROM (IC semiconductor).
The above control is performed by outputting a control signal corresponding to one piece of data that has been inputted to the controller.

<Effects of the Invention> As described above, according to the present invention, as shown in the comparison curve between the engine of the present invention shown by the solid line and the light oil diesel engine shown by the dotted line in FIG. This is achieved over the entire load range from load to high load, eliminating abnormal combustion due to premature ignition in the high load range, and
Controlling the excess air ratio in the low load range 1111J has the advantage of providing an alcohol-fueled internal combustion engine with stable combustion, low noise, and improved performance.

Ru.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an internal combustion engine according to the present invention, FIG. 2 is an explanatory diagram of a control operating region, and FIG. 3 is a thermal efficiency characteristic diagram according to the present invention. 1. Fist engine body, 2. Fist tank, 3. e. injection pump, 4. Injection nozzle, 5. Alcohol pump,
6-11 evaporator, No. 7...Reformer, 8...Solenoid flow control valve, 9φ...Intake pipe, 10φ...Spark plug, 11
-...Intake control valve, 12...-Controller, 13...Igniter.

Claims (3)

[Claims] (1) Equipped with a two-system fuel supply system that can be switched according to engine operating conditions: a direct injection means that sprays alcohol fuel into the combustion chamber as a liquid, and a means that supplies reformed gas to the intake pipe. An internal combustion engine using alcohol as fuel, characterized in that it is equipped with an intake control valve and its control device that control the amount of intake air into the combustion chamber in accordance with the operating conditions of the engine, and a spark plug that ignites the fuel. institution. (2) The fuel supply device directly injects fuel when the engine is under high load and medium load, and directly injects a small amount of fuel when the engine is under low load, and supplies most of the reformed gas. An internal combustion engine that uses alcohol as fuel. (3) The intake control device adjusts the amount of intake air by fully opening the intake control valve when the engine is at high load, throttles it at medium loads, and further throttles it at low loads to maximize the thermal efficiency of the engine. An internal combustion engine using alcohol as fuel according to claim 1, wherein the internal combustion engine is controlled so that the following is achieved.